Automatic drycleaning still



De'c. 5, 1961 J. c. SMITH ETAL 3,011,956

AUTOMATIC DRYCLEANING STILL Filed March l5, 1960 2 Sheets-Sheet 1 I i /5G: 3 I// DMSDQJ Dec. 5, 1961 Filed March 15, 1960 J. C. SMITH ETALAUTOMATIC DRYCLEANING STILL 2 Sheets-Sheet 2 United States PatentFatented Dec. 5, 'el

tice

Filed lvlar. 15, i959, Ser. No. 15,172 2 Claims. (Cl. 2912-266) rthisinvention relates to a distillation process and to an automatic stillused in drycleaning.

The dri/cleaning process ordinarily used in the cleaning of garmentsremoves not only solid soils but also soluble soils, fatty acids, bodysalts and color dyes from the garments being cleaned and holds them inthe cleaning solvent. This is undesirable for several rea-sons. In thei'irst place, the presence of dyes in the cleaning solvent causesdulling of light colored fabrics by deposition. Secondly, fatty acidsand body salts give the solvent an unpleasant odor which is retained bythe garments after cleaning. And third, the soluble soils (which areobvi ously not a desirable ingredient in the cleaning solvent) are notreadily removed by the systems diatomaceous filter.

The introduction of certain types of filter aids, such as activatedgranular carbon, will remove part of the soluble soils but the use ofthese aids is greatly restricted by the fact that they rapidly becomesaturated and form an impervious lm over the filter elements, thusreducing the ow through the elements to such an extent that cleaningefficiency is greatly reduced.

Accordingly, a preferred method of removing soluble soils from thecleaning solvent is by distillation.

Drycleaning stills ordinarly used with drycleaning processes whichutilize a synthetic solvent such as perchlorethylene, are of theatmospheric type, that is, they are vented to the drycleaning machine,or to the room or atmosphere. The soluble soils encountered ordinarilyhave a higher boiling point than the cleaning solvent and it istherefore the solvent which is vaporized in the still. The solventvapors are conducted to a condensing area leaving the soluble soils inthe boil chamber of the still. These soils are accumulated until theyare present 'Ln suiiicient quantities to raise the boiling point of themixtures of solvent and residues to such a high value that thedistillation rate is greatly reduced. At this point it is customary todrain the residues from the boil chamber to a waste pipe or receptacle.

With the advent of solvent-soluble soaps and the introduction into thesolvent of small controlled amounts of moisture to assist in thedrycleaning process, the problems of distillation have been increasedbecause the soap and moisture introduced into the boil chamber alongwith the solvent interact with the residues of the distillation to causefoaming. vi/hen foaming occurs, the dirty solvent (that is, the solventcontaining residues) is carried into the condensing area from there isreturned to the solvent storage tank. This, of course, is to be avoided,and it has heretofore been the duty of the operator to Watch for foamingand to take the necessary action to stop it when it occurs. When foamingoccurs which is not detected by the operator, and if it continuesV 2when he does this, the disti lation rate is also greatly reduced.

Another means of controlling foaming is to introduce a cold solventspray directed toward the surface of the solvent in the boil chamber.Although this method has been moderately successful, it likewise greatlyreduces the distillation rate of the still.V

' Our present invention provides a distillation process and still inwhich foaming is automatically controlled Without apprecably reducingthe distillation rate.

The still of our present invention is especially suited for use withbatch rinse processes.

Our invention will become clear from a consideration of the followingdetailed description of a preferred embodiment illustrated in thedrawing in which:

FIG. l is a front elevational View, partly in section, of a stillembodying our present invention; and

FG. 2 is a side elevational view, partly in section, of the still ofFlG. l.Y

ln describing the preferred embodiment of the invention illustrated inthe drawing, specific terminology has been resorted to for the sake ofclarity. However, it is not the intention to be limited to` the specilicterms so selected, and it is to be understood that each specific terreincludes all technical equivalents which ope-rate in o. similar mannerto accomplish a similar purpose.

Referring now to the drawing, solvent is introduced through a conduitconnection l (FlG. 2) into the boil chamber 2 thru a conduit line fromthe machine not shown. When the level in the boil chamber 2 is enough todisplace the lloat of float contro-l le (llG. l), anelectricallyoperated solenoid valve 3 is energized automatically to allow steam toenter steam coil l to boil the solvent contained ln the boil chamber.Vapors generated duringl the boil rise through duct S to entercondensing chamber 6. When these vapors contact the cold surfaces ofcondensing coil 7 they are condensed and run down into the trough 8formed between duct 7 and the side of condensing chamber o.

A valve 9 located in a discharge conduit from trough 8 is normallyclosed but has a small orice hole in the gate.

The condensate level builds up in the trough 3 until it flows out a pipeconduit l@ into the side of after cooler Water separator 1l. 8 iscoolcd'below the condensing temperature before leaving the condensingchamber 6. 'Ihe internal construction of water separator 1i is such thatas the condensed solvent rises through channel 12 of separator 11 itpasses through an orifice 13 into a rag container chamber 2'! and thenpasses through the rags, Which'remove minute traces of Water, into apipe conduit i4 and then into the solvent storage tank. A sight glass 15is provided for a visual check of the condition of the condensate. Wateris displaced to the top of the liquid level in water Vseparator 12 andflows to waste through pipe conduit 16.

Cooling coil 17 within the water separator further reduces thetemperature of the condensate before it is returned to the storage tank.

in accordance with one feature of the automatic still of our presentinvention, when enough solvent is boiled out of the chamber 2 to dropthe solvent to a selected low level, the float level control 1d'operatesV automatically to de-energize the solenoid-operated controlvalve 3, thus automatically shutting olf steam toA steam coils 4. Inaccordance with a second feature of the automatic still of our presentinvention, a light source 19 and a photoelectric cell 29 are located onopposite sides of the boil chamber 2 near the top thereof. Theseelements 19, 2tlare so located, in line with each other, .thatY lightfromV source 19 is beamed directly on the sensing element of photo cell2l?. interposed between light source 19 and The condensate retained intrough aeiasee photo-electric cell 2.0 on each side of boil chamber Y2is a glass lens'21, 21. These lenses also seal ot the vapors fromelements 19, 29. The light intensity of source 19 is suicient topenetrate the vapors formed within the boil chamber and energizesuiciently the cell 20. However, should the solvent within the boilchamber 2 foam up suiiiciently to reach the beam of light extendtingacross the top of the boil chamber, the light from source 19 will notpenetrate adequately the denser dark foaming liquid. Thus, light fromsource 19 is effectively removed from the photo cell 20, and when thisoccurs power to the electrically operated valve 3 is interrupted andsteam to steam coils 4 is shut o. With the removal of the heat supply,the foam blanket drops and as soon as the foam drops below the beam oflight, the light from source 19 again reaches the photo cell 20 insuicient amount to close the circuit.

to electric valve 3 and restore steam to coils 4. The foam thereuponrises, the beam of light is again intercepted, and the heat is againshut ot. The action is rapid, and results in heat being applied in apulsating manner with such rapidity as to provide almost continuousdistillation, even when a heavy layer of foam exists which extends fromthe level of the solvent to the beam of light. It will be seen then thatwhile heat is applied in such volume as to maintain a high rate ofdistillation the foam blanket is prevented automatically from risingsuihciently to enable Vfoam from reaching duct 5 and contaminating thecondensate.

In accordance with still another feature of our invention, steam coil 4is deliberately sized to supply more heat than the condensing coil 7 canremove so that as residues build up in boil chamber 2, raising theboiling point of the solution in the boil chamber, suicient heat willstill be supplied to cause the solution to boil, thus maintaining a'highdistillation rate. In accordance with this third feature of ourautomatic still, a heat-sensitive thermo-switch 22 is located within theupper-portion of the condensing chamber 6 and so set that if .hotsolvent vapors reach its element instead of relatively cool air it willoperate to break the power supply to the electric valve 3, therebyautomatically removing the steam heat supply to coils 4 until such timeas the Yvapors in the condensing chamber 6 drop in level and allow theatmospheric air to cool the area surrounding the element of thermoswitch2,2 suiiiciently to cause the heat-sensitive element to return to itsformer position, thus reenergizing valve 3. It will be seen that thethermo-switch 22 acts as a safety device against the boil-up rate ofsolvent vapors exceeding the condensing capacity of `the Vcoil 7 andthereby allowing said vapors to escape into the room, which mightotherwise happen when the boil chamber contains a solution of lowresidue content. Y Asta further feature of the still of our presentinvention, a pipe conduit 23 is provided which connects with conduit 14so that if the valve 24 in pipe conduit '23 is manually opened and avalve (not shown) between sight glass 15 and the storage tank ismanually closed, the condensate in conduit 14 from the Water separator12 is directed back tothe boil chamber 2. Thus, if an inspec- Y tion ofthe condensate through sight glass 15 reveals that,

through a malfunction of the controls, the condensate has becomecontaminated, the above-mentioned manually op- Y erated valves provide ameans of diverting the condensate through the conduit 2,3 to boilchamber 2 and preventing it from reaching the storage tank.

The still also includes a drip trough in duct 5 to catch condensateformed on this duct and conduct such rcondensate through pipe conduit 26to the water separator 12. Y

It will be seen that the still according to our invention providesmeans: (l) for the automatic turning on :and oi of steam to steam coils4 in response to the foam contamination; midV although providing fordistillation at a high rate (3) for preventing the distillation fromexceeding the condensing capacity of the condensing coil. Each of themeans (l), (2), (3) just mentioned operates independently to de-energizethe solenoid valve 3, as by opening a relay-operated series switch.

Although not shown, it will be understood that means are provided forlocking out the automatic circuit to allow the still 4to be cleaned bystripping of the solvent from the residue.

While the preferred embodiment of this invention has been described insome detail, it will be obvious to one skilled in the art that variousmodifications may be made without departing from the invention ashereinafter claimed.

Having thus described our invention, we claim:

l. A still for distilling soiled solvent at a high distillation ratewithout requiring manual attention, said still comprising; a boilchamber for boiling the mixture of solvent and soils; a relatively largesupply of heat for said boil chamber sufiicient in quantity to continueto boil said mixture at a high rate despite a rise in the boiling pointof the mixture as the solvent is distilled therefrom and the percentageof contaminate residue increases; a condensing chamber'locatedV aboveand in communication with said boil chamber for condensing the solventvapors received from said boil chamber; sensing means providing a beamof light across the upper part of said boil chamber for sensing thatfoam has risen in said boil chamber to the height of said light beam;means coupled to said sensing means for shutting off the supply of heatto said boil chamber when said foam reaches said beam of light and forrestoring the supply of heat when the foam subsides below said beam oflight, thereby to proide a pulsating supply of heat to said boil chamberand thereby to permit solvent distillation to take place at a high ratewithout permitting foam to enter said condensing chamber; and heatsensitive means in the upper part of said condensing chamber coupled tomeans operative in response to the temperature at said upper levelrising above a pre-determined value for shutting oli the supply of heatto said boil chamber so long as said temperature at said level is abovesaid pre-determined value and for restoring the supply of heat when thetemperature at said upper level falls below said pre-determined value,thereby to permit solvent distillation to take place at a high ratewithout exceeding the condensing capacity of said condensing chamber.

2. An automatic still for distilling soiled non-aqueous solvent, saidstill comprising: a boil chamber for receiving the soiled solvent; meansresponsive automatically to the level of the soiled solvent in said boilchamber for turning on a supply of heat to said boil chamber when saidlevel reaches a pre-selected maximum and for automatically shutting oisaid supply of heat when said level is reduced to a pre-selectedminimum, thereby to prevent boiling said chamber dry; a condensingchamber above and in communication withsaid boil chamber for condensingsolvent vapors received from said boil chamber; heat-sensitive controlmeans in the upper part of said condensing chamber for shutting od thesupply of heat in said boil chamber when the level of solvent vapors insaid condensing chamberV rises suiiiciently to reach said heat sensitivemeans and for restoring said heat supply when said level falls belowsaid heat sensitive means, thereby to permit solvent distillation toYtake place at a high rate without exceeding the capacity of said Vcondensing chamber; and means responsive to the level solvent level inboil chamber 2, thus preventing boiling Y of foam generated in said boilchamber for automatically shutting oii the supply of heat to said boilchamber when said foam rises to a pre-selected level and for restoringsaid heat supply as soon as said foam drops below said pre-selectedlevel, thereby to permit solvent distillation to take place at a highrate without permitting foam to reach said condensing chamber, saidmeans responsive to the foam level in said boil chamher including alight source and a light-responsive cell at spaced-apart locations inthe upper part of said boil chamber, thereby to transmit a horizontalbeam of light from said light source across the upper part of saidchamber to said light-responsive cell.

UNITED STATES PATENTS Coleman June 19, 1900 Powell et al. Aug. 24, 1937Clark Oct.,22, 1940 Blakeslee Dec. 3, 1940 Black May 4, 1943 `lohnstonJan. 16, 1951 Whittington Apr. 22, 1952 St. Palley Nov. 27, 1956

